1. Field of the Invention
The invention relates in general to printing machines and in particular to a new and useful form cylinder for rotary intaglio printing presses provided with flexible printing plates.
2. Description of the Prior Art
The problem of equipping form cylinders for intaglio printing presses with flexible printing plates has been known for a long time. Care must be taken that the flexible printing plates are clamped tightly and uniformly on the cylinder body, and that the butt joint is closed completely so that no ink can be deposited therein and the wiper can slide smoothly over it.
Several solutions are known as attempts to meet these requirements:
German Patent No. 541,478 shows a device for clamping flexible printing plates on the form cylinder of intaglio printing presses where the bent-off ends of the printing plates are held in clamping strips and stressed by means of a wedge both in radial and in tangential directions. This device is only suitable for form cylinders which have the width of the printing plates, and it has a disadvantage that the form cylinder must be removed from the machine to change the printing plates, since the clamping strips and the wedge can only be introduced into the dovetailed grooves at the front end.
It is already known from German Patent No. 567,546 that the ends of the printing plates cannot be bent off so sharply that no interwall receiving ink is formed at the plate butt. This fact is taken into consideration by pressing the ends of the printing plates against a filler, which is subsequently smoothed and hardened on the outer surface. This procedure is cumbercome and time consuming, just like the casting of the plate butt, as it is known from DOS 24 09 456 and German design patent No. 75 25 069.